translucent. Bic makes this pen at its own plants in Europe. In September 2006, the Bic Cristal was declared the best selling pen in the world after the 100 billionth was sold. Design The Museum of Modern Art in New York City recognised the Bic Cristal's industrial design by introducing it into the museum's permanent collection. Its hexagonal shape resembles the typical wooden pencil and grants strength and three grip points giving high writing stability. The pen's transparent polystyrene barrel and polypropylene tube show the ink-level. The only exception is the BIC Cristal UP, a pen marketed by Bic that supposedly creates more vivid lines when used. These pens have a white barrel and, depending on what color the ink reservoir contains, a small area of the pen barrel and cap with the corresponding ink color. A tiny hole in the barrel's body maintains the same air pressure inside and outside the pen. The pens' ink color has many different varieties, ranging from the 'classic' colors (blue, black, red, and green), to pink and purple. The thick ink flows down due to capillary action from the tube inside the barrel, to feed the ball bearing, which spins freely within a brass tip. In 1961, the stainless steel ball was replaced with much harder tungsten carbide. This ballpoint is first vitrified by heat, then ground down and milled to an accuracy of between spinning plates coated with industrial diamond abrasives. Since 1991 the pen's streamlined polypropylene cap has had a small hole to reduce the risk of suffocation if the cap is inhaled. Polypropylene is used instead of polystyrene because it absorbs impact better, reducing the chance of the pen cracking or splitting if it is dropped onto the cap. The pen's dimensions are with the cap, or 14.5 by 0.7 cm without the cap. The Cristal's design has become a target for counterfeiters, especially from the Far East and in particular from China. Their pens are manufactured at a cheaper price and made to appear similar to the original. One Kenyan pen manufacturer reportedly lost KSh.100,000,000/= (approx. $1.3 million USD at 2009 exchange rate) to fake copies, forcing them to negotiate cheaper licensing from Bic. Spin-offs Bic Cristal for Her In 2012, Bic marketed a spin-off product named the "Bic Cristal for Her". The pen, similar to the original, was supposedly designed specifically for women, and was sold in pink